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| 型号： | MAX6858UK21D4-T |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 电源管理 |
| 英文描述： | Nanopower µP Supervisory Circuits with Manual Reset and Watchdog Timer |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5 |
| 封装： | MO-178AA, SOT-23, 5 PIN |
| 文件页数： | 4/17页 |
| 文件大小： | 489K |
| 代理商： | MAX6858UK21D4-T |
MAX6854/MAX6855/MAX6856/MAX6858/MAX6860–MAX6869
Transient Immunity
In addition to issuing a reset to the P during power-up,
power-down, and brownout conditions, the MAX6854/
MAX6855/MAX6856/MAX6858/MAX6860–MAX6869 are
relatively immune to short-duration supply transients, or
glitches. The Maximum VCC Transient Duration vs. Reset
Threshold Overdrive graph in the Typical Operating
Characteristics shows this relationship.
The area below the curve of the graph is the region in
which these devices typically do not generate a reset
pulse. This graph was generated using a falling pulse
applied to VCC, starting 100mV above the actual reset
threshold, VTH, and ending below this threshold (reset-
threshold overdrive). As the magnitude of the transient
increases, the maximum allowable pulse width
decreases. Typically, a 100mV VCC transient duration
of 40s or less does not cause a reset.
Interfacing to Other Voltages for Logic
Compatibility
The open-drain RESET output can be used to interface
to a P with other logic levels. As shown in Figure 4, the
open-drain output can be connected to voltages from 0
to 5.5V.
Generally, the pullup resistor connected to RESET con-
nects to the supply voltage that is being monitored at
the IC’s VCC input. However, some systems use the
open-drain output to level-shift from the monitored sup-
ply to reset circuitry powered by another supply voltage.
Keep in mind that as the supervisor’s VCC decreases,
so does the IC’s ability to sink current at RESET.
Ensuring a Valid
RESET Down to VCC = 0V
(Push-Pull
RESET)
When VCC falls below 1.1V, RESET’s current-sinking
capability declines drastically. The high-impedance
CMOS logic inputs connected to RESET can drift to
undetermined voltages. This presents no problems in
most applications, since most Ps and other circuitry
do not operate with VCC below 1.1V.
In those applications where RESET must be valid down
to 0, add a pulldown resistor between RESET and GND
for the MAX6854/MAX6858/MAX6861/MAX6864/
MAX6867 push-pull outputs. The resistor sinks any stray
leakage currents, holding RESET low (Figure 5). Choose
a pulldown resistor that accommodates leakages, such
that RESET is not significantly loaded and is capable of
pulling to GND. The external pulldown cannot be used
with the open-drain reset outputs.
Watchdog Software Considerations
One way to help the watchdog timer monitor software
execution more closely is to set and reset the watchdog
Nanopower P Supervisory Circuits with
Manual Reset and Watchdog Timer
12
______________________________________________________________________________________
MAX6856
MAX6860
MAX6863
MAX6866
MAX6869
GND
N
RESET
1.8V
VCC
GND
3.3V
P
100k
Figure 4. Interfacing with Other Voltage Levels
VCC
2M
MAX6854
MAX6858
MAX6861
MAX6864
MAX6867
GND
RESET
Figure 5. Ensuring RESET Valid to VCC = Ground
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX6858UK21D5+T | 功能描述:监控电路 Single nPower Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX6858UK21D5-T | 功能描述:监控电路 RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX6858UK21D6+T | 功能描述:监控电路 Single nPower Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX6858UK21D6-T | 功能描述:监控电路 RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX6858UK22D1+T | 功能描述:监控电路 Single nPower Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
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